The new Transfer v2 models can each be expanded to carry an additional bike with the 1-Bike Add-On. Increase the capacity of your 1-Bike, 2-Bike, or 3-Bike rack to carry up to *4-bikes with all the features you expect at a price that's unexpected. *Add-Ons cannot be stacked. Only a single 1-Bike Add-On can be attached to Transfer v2 models. The 1.25"-2" Transfer v2 2-bike (SKU T202B) model cannot take a one bike add-on.